package euler
import scala.io.Source
import scala.annotation.tailrec

/**
 * In the 2020 grid below, four numbers along a diagonal line have been marked in red.
 * 
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
The product of these numbers is 26  63  78  14 = 1788696.
What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) 
in the 2020 grid?
 */
object Problem11 extends Problem {

  override val problemNumber = 11
  
  def resolve(): Unit = {
    val gridSource = Source.fromFile("/home/gustavo/workspace/euler/src/euler/problem11/grid.txt")
    val gridStr = gridSource.mkString
    gridSource.close()
    val grid = gridStr.split("\n").toList.map(row => row.split(" ").toList.map(element => element.toInt))
    grid.map(row => println(row))
    println("Greatest product = " + greatestProduct(0, 0, 0, grid))
  }

  def getGreatest(x:Long, y:Long): Long = {
    if (x > y) x else y
  }
  
  @tailrec
  def greatestProduct(row:Int, col:Int, greatest:Long, grid:List[List[Int]]): Long = {
    if (row == 19 && col == 19) return greatest
    var product = greatest
    product = getGreatest(product, multiplyRight(row, col, grid))
    product = getGreatest(product, multiplyLeft(row, col, grid))
    product = getGreatest(product, multiplyUp(row, col, grid))
    product = getGreatest(product, multiplyDown(row, col, grid))
    product = getGreatest(product, multiplyUpLeft(row, col, grid))
    product = getGreatest(product, multiplyUpRight(row, col, grid))
    product = getGreatest(product, multiplyDownLeft(row, col, grid))
    product = getGreatest(product, multiplyDownRight(row, col, grid))
    val nextRow = if (col == 19) row + 1 else row 
    val nextCol = if (col == 19) 0 else col + 1
    greatestProduct(nextRow, nextCol, product, grid)
  }
  
  def gridValue(row:Int, col:Int, grid:List[List[Int]]): Int = {
    var value = 1
    try {
      value = grid(row)(col)
    } catch {
      case e => value = 1
    }
    return value
  }
  
  def multiplyRight(row:Int, col:Int, grid:List[List[Int]]): Long = {
    gridValue(row,col,grid) * gridValue(row,col + 1,grid) * gridValue(row,col + 2,grid) * gridValue(row,col + 3,grid) 
  }
  
  def multiplyLeft(row:Int, col:Int, grid:List[List[Int]]): Long = {
    gridValue(row,col,grid) * gridValue(row,col - 1,grid) * gridValue(row,col - 2,grid) * gridValue(row,col - 3,grid) 
  }
  
  def multiplyUp(row:Int, col:Int, grid:List[List[Int]]): Long = {
    gridValue(row,col,grid) * gridValue(row - 1,col,grid) * gridValue(row - 2,col,grid) * gridValue(row - 3,col,grid) 
  }
  
  def multiplyDown(row:Int, col:Int, grid:List[List[Int]]): Long = {
	gridValue(row,col,grid) * gridValue(row + 1,col,grid) * gridValue(row + 2,col,grid) * gridValue(row + 3,col,grid) 
  }
  
  def multiplyUpLeft(row:Int, col:Int, grid:List[List[Int]]): Long = {
	gridValue(row,col,grid) * gridValue(row - 1,col + 1,grid) * gridValue(row - 2,col - 2,grid) * gridValue(row - 3,col - 3,grid) 
  }
  
  def multiplyUpRight(row:Int, col:Int, grid:List[List[Int]]): Long = {
	gridValue(row,col,grid) * gridValue(row - 1,col + 1,grid) * gridValue(row - 2,col + 2,grid) * gridValue(row - 3,col + 3,grid) 
  }
  
  def multiplyDownLeft(row:Int, col:Int, grid:List[List[Int]]): Long = {
	gridValue(row,col,grid) * gridValue(row + 1,col + 1,grid) * gridValue(row + 2,col - 2,grid) * gridValue(row + 3,col - 3,grid) 
  }
  
  def multiplyDownRight(row:Int, col:Int, grid:List[List[Int]]): Long = {
	gridValue(row,col,grid) * gridValue(row + 1,col + 1,grid) * gridValue(row + 2,col + 2,grid) * gridValue(row + 3,col + 3,grid) 
  }
  
}